This is one of the many trails at Glacier NP. It offers great vistas of lakes and forested areas. You'll have a chance to see wildlife including mountain goats.
It is a medium type of trail, not too hard for two 69 year old.

Starts out steep, but don't let that scare you. After the initial ascent the trail is fairly gentle. You'll pass through several types of terrain, from alpine meadow to cedar and pine woods that smell amazing, with lots of beautiful views out across the glacier-dug valley. There's quite a bit of water crossing the trail, as the peaks to the north are around 1500' above the trail and carry snow year-round in places, so bring some good hiking footwear. Also bring your filter and fill your flask from the glacier meltwater! In early September there were still a good bit of thimbleberries and huckleberries to snack on as well. There's even a rather... rustic... pit toilet on a little spur about halfway to the lake.
When you get to the end there is a nice little "beach" for relaxing, eating lunch, and chatting with your trailmates; or if solitude is more your thing, there is a good bit of accessible shoreline to explore away from the inevitable crowds. There is often a ranger there explaining various features of the lake, the glacier, and the valley. Watch out for the ground squirrels, they'll raid your pack for snacks if you're not careful!